Transforming to rectangular coordinates

This function is used for conversion of the arched image to rectangular one, so the single admissible source form to digitize is a rectangular image.

To transform image it is required to depress the Arc button at the main window just after loading of arched PCX-file. New window will emerge.

In general case it is supposed that pen shoulder radiuses may be different on one seismogram for different traces. So the coordinate transformation is being performed inside "layers", or "trace corridor". Each layer is placed symmetrically relatively to the axis, and has its own width (thickness) and radius value.

A part of image, situated out of chosen layers, is not affected by the program. But it's being completely erased to avoid the dirt due to pen splush. Though the user manipulate with layers subsequently, the coordinate transformation is processed at once for all layers simultaneously.

Activate the Set axes mode and draw axis. The control number of axes will be written in relevant string of the window. The order of axes may be arbitrary. Besides you are able to define more precisely a location of axis by clicking the left mouse button near the old axis. In Del axes mode these actions will cause the mentioned axes to be deleted.

Activate the Set layer mode and draw layer's boundaries. Generating the axis is required for further estimation of pen shoulder radius and transforming of arched coordinates. If you know exactly the physical size of pen radius you should merely enter this value (in pixels) in Average radius command string and press the Apply. Notice, that you should take into account the real resolution of computer monitor. If you do not know the physical size of pen radius, you should perform a number of graphic measurements. To define a radius you need to take two points on the well visible arc: one on the axis (on diameter) and one far from axis. The program estimates a radius size and writes a value onto the screen. In order to exclude a random factor, we should repeat this experience several times and to confirm the average by clicking Apply button. Total number of passes performed is shown in the string, named as Number of test. If you are not satisfied with the results, you may cancel the radius by clicking the button Cancel radius and repeat measurements again. If radiuses for different layers are equal (default regime), all layers are set simultaneously by just one clicking the button. If everything is OK, you should press the upper Transforming button to start the transforming procedure.

Further User's interaction is the same, as with ordinary rectangular seismogram (fig.7). The lower part of Arc window is also intended for cleaning of vertical scale lines.